Tafsir of Al Imran 3:174

(So they returned) is a conjunction to an elided verb indicated by the context, meaning: they went out to them and returned.

(With a favor) is in the position of a state (hal) for the pronoun in "returned" (inqalabu). It is also permissible for it to be a direct object. In the first case, the particle "ba" is for transition (ta'diyah), and in the second, it denotes accompaniment (musahabah). The tanwin in both estimations is for magnification, meaning: (with a favor) magnificent, the extent of which cannot be measured.

(From Allah) is an adjective for "favor," reinforcing its magnificence. The intended meaning is safety, as stated by Ibn Abbas, or steadfastness in faith and obedience to Allah the Exalted and His Messenger—may Allah bless him and grant him peace—as stated by al-Zujjal, or the defeat of the enemies of Allah the Exalted from a distance, as was said, or a combination of these matters, as we maintain.

(And grace) which is the profit in trade. Al-Bayhaqi narrated from Ibn Abbas that a caravan passed by during the season, and the Messenger of Allah—may Allah bless and exalt him—purchased from it and made a profit, which he then distributed among his companions; that is the grace.

Ibn Jarir narrated from al-Suddi that he said: When the Messenger of Allah—may Allah bless and exalt him—went out for the minor Battle of Badr, he gave his companions dirhams with which they traded during the season, and they acquired profit. From Mujahid: the grace is what they acquired of trade and reward.

(No harm touched them) meaning: killing did not befall them—this is what is narrated from al-Suddi—or no one harmed them—this is what is narrated from the Sage (Ibn Abbas). The sentence is in the position of an accusative state (hal) for the subject of "returned," or for the implicit pronoun in "with a favor" if it is considered a state. The meaning is: they returned, favored and absolved of harm. When a state-sentence has a verb that is a present tense negated by "lam" and contains a pronoun referring to the subject of the state, the inclusion of the conjunction "wa" is permissible, as is its omission.

(And followed) is a conjunction to "returned." It is also said to be a state for its pronoun with the implicit "qad" (already), meaning: they were followed in all that they were given, or in going out to meet the enemy.

(The pleasure of Allah) which is the pivot of all goodness.

(And Allah is the possessor of great grace) as He favored them with what He favored them with, and in what has preceded. Appending this verse, which includes the encompassing noble name and the attribution of "possessor of grace" to Him, as well as describing that grace as "great," serves as an indication that those who stayed behind missed out on a great matter whose reality cannot be fathomed, and they are worthy of feeling regret over it, a regret beyond which there is no other.